Show HN: Optimal UX – Server-side A/B testing that runs before page load (optimalux.com)

Optimal UX runs experiments directly on the server side through a Cloudflare Worker, meaning variations are applied before the page even reaches the browser.

The core idea is to intercept and modify the HTML stream at the edge, which eliminates client-side overhead. For websites using Cloudflare, it's just a matter of installing the Smart Agent. The same agent works seamlessly with React, Vue, and other frontend frameworks when client-side testing is needed.

One unexpected benefit that emerged during development was the ability to quickly apply HTML patches. This turned out to be super useful for SEO tweaks - you can update meta tags, headings, or content structure without deploying new code.

Tech stack: -Edge computing (Cloudflare Workers) - Streaming HTML parser - Framework-agnostic client library (~3KB gzipped)

Would love feedback from anyone doing A/B testing at scale. This is my first time building something for edge computing and I learned a ton about HTML streaming and performance optimization.

I'm particularly curious: - Has anyone else encountered performance issues with client-side A/B testing tools? - For those running tests on high-traffic sites, how do you handle the performance impact? - What's your experience with edge computing for similar use cases?